Drifting kart

ABSTRACT

Drifting karts in accordance with embodiments of the invention are described that include a front wheel drive train and rear caster wheels that can be dynamically engaged to induce and control drift during a turn. One embodiment of the invention includes a chassis to which a steering column is mounted, where the steering column includes at least one front steerable wheel configured to be driven by an electric motor, a battery housing mounted to the chassis, where the battery housing contains a controller and at least one battery, wiring configured to provide power from the at least one battery to the electric motor, two caster wheels mounted to the chassis, where each caster wheel is configured to rotate around a rotational axis and swivel around a swivel axis, and a hand lever configured to dynamically engage the caster wheels to induce and control drift during a turn.

RELATED APPLICATIONS

Certain related applications are listed in an application data sheet(ADS) filed with this application. The entirety of each of theapplications listed in the ADS is hereby incorporated by referenceherein.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to the field of motorized vehicles and,more specifically, to a kart type vehicle used for racing, andrecreational entertainment.

Karting or kart racing is a popular open-wheeled motor sport withsimple, small four wheeled vehicles called karts, go-karts, orgearbox/shifter karts depending on the design. Karts vary widely inspeed and can reach speeds exceeding 160 miles per hour, while kartsintended for the general public may be limited to speeds of no more than15 miles per hour. 2-stroke or 4-stroke engines are typically used topower karts. However, a number of karts are powered by electric motorsincluding DC electric motors.

Karts are typically rear wheel drive and are steered using the frontwheels of the kart. Karts generally lack suspension so that the chassisof the Kart absorbs much of the vibration experienced during motion. TheKart chassis is designed to be flexible enough to work as a suspensionand stiff enough not to break or give way during a turn. The chassis iscommonly constructed from hollow tubes. For stability the driver of akart is typically seated as low to the ground as possible. Lowering theheight of the combined center of mass of the driver and kart reduces thelikelihood that the kart will roll during a high speed maneuver.

Karts typically do not have a differential. The lack of a differentialmeans that one rear tire must slide while cornering. Sliding can beachieved by designing the chassis so that the inside rear tire lifts upslightly when the kart turns the corner. This allows the tire to losesome of its grip and slide or lift off the ground completely.

Drifting refers to a driving technique and to a motor sport where thedriver intentionally oversteers, causing loss of traction in the rearwheels through turns, while preserving vehicle control and a high exitspeed. A vehicle is said to be drifting when the rear slip angle isgreater than the front slip angle prior to the corner apex, and thefront wheels are pointing in the opposite direction to the turn, and thedriver is controlling those factors. Techniques for inducing driftinclude a hand brake drift. During a hand brake drift, the hand brakelever is used to stop the rear wheels, upsetting their grip and causingthem to drift.

Drifting has become a competitive sport where drivers compete in rearwheel drive cars, and occasionally all wheel drive cars, to earn pointsfrom judges based on various factors including line, angle, speed andshow factor. Line involves taking the correct line, which is usuallyannounced beforehand by judges. The show factor is based on multiplethings, such as the amount of smoke, how close the car is to the wall,and the crowd's reaction. Angle is the angle of a car in a drift, speedis the speed entering a turn, the speed through a turn, and the speedexiting the turn. Drift cars are typically light to moderate weight rearwheel drive coupes and sedans ranging from 200-1000 bhp. In almost allinstances, drift cars include a mechanical limited slip differential.

SUMMARY OF THE INVENTION

Drifting karts in accordance with embodiments of the invention include afront wheel drive train and rear caster wheels that can be dynamicallyengaged to induce and control drift during a turn. One embodiment of theinvention includes a chassis to which a steering column is mounted,where the steering column includes at least one front steerable wheelconfigured to be driven by an electric motor, a battery housing mountedto the chassis, where the battery housing contains a controller and atleast one battery, wiring configured to provide power from the at leastone battery to the electric motor, two caster wheels mounted to thechassis, where each caster wheel is configured to rotate around arotational axis and swivel around a swivel axis, and a hand leverconfigured to dynamically engage the caster wheels to induce and controldrift during a turn.

In a further embodiment, the two caster wheels are mounted to thechassis via a rotatable member that is connected to the hand lever, androtation of the hand lever rotates the caster wheels from a firstposition where the caster wheels are aligned so that the weight on thecaster wheels limits the ability of the caster wheels to swivel abouttheir swivel axes, to a second position where the caster wheels arealigned so that they are free to swivel about their swivel axes.

In another embodiment, the steerable wheel is mounted to a zero camberzero rake fork.

In a still further embodiment, the steering column is configured torotate through 360 degrees.

In still another embodiment, each caster wheel is configured to rotate360 degrees around its rotational axis.

In a yet further embodiment, the electric motor is a variable speedelectric motor, and the power delivered to the variable speed electricmotor is controlled by an acceleration pedal.

Yet another embodiment also includes a seat mounted to the chassis andpositioned in front of the battery housing.

In a further embodiment again, the seat is mounted to the chassis sothat a steering wheel fixed to the steering column and the hand leverare within reach of a driver seated in the seat and so that the driveris seated low to the ground.

Another embodiment again also includes a pair of fixed wheels connectedvia an axle. In addition, the hand lever is configured to raise andlower the pair of fixed wheels and the casters are mounted to thechassis and the hand lever engages the caster wheels by raising thefixed wheels.

In a further additional embodiment again, the fork is a zero camber zerorake fork.

In another additional embodiment again, the steering column isconfigured to rotate through 360 degrees.

In a still yet further embodiment, each caster wheel is configured torotate 360 degrees around its rotational axis.

In still yet another embodiment, the electric motor is a variable speedelectric motor, and the power delivered to the variable speed electricmotor is controlled by an acceleration pedal.

A still further embodiment again also includes a seat mounted to thechassis and positioned in front of the battery housing.

In still another embodiment again, the seat is mounted to the chassis sothat a steering wheel fixed to the steering column and the hand leverare within reach of a driver seated in the seat and so that the driveris seated low to the ground.

Another further embodiment includes a hollow tube chassis to which asteering column is mounted, where the steering column includes at leastone front steerable wheel mounted to a zero camber zero rake fork thatis configured to rotate through 360 degrees and where the at least onesteerable wheel is configured to be driven by a variable speed electricmotor, a battery housing mounted to the chassis, where the batteryhousing contains a controller and at least one battery, wiringconfigured to provide power from the at least one battery to thevariable speed electric motor, an acceleration pedal connected to athrottle that controls the power delivered by the at least one batteryto the variable speed electric motor, two caster wheels mounted to thechassis via a rotatable member, where each caster wheel is configured torotate 360 degrees around a rotational axis and swivel 360 degreesaround a swivel axis, a hand lever connected to the rotatable member,where rotation of the hand lever dynamically engages the caster wheelsto induce and control drift during a turn by rotating the caster wheelsfrom a first position where the caster wheels are aligned so that theweight on the caster wheels limits the ability of the caster wheels toswivel about their swivel axes, to a second position where the casterwheels are aligned so that they are free to swivel about their swivelaxes, and a seat mounted to the chassis and positioned in front of thebattery housing so that a steering wheel fixed to the steering columnand the hand lever are within reach of a driver seated in the seat andso that the driver is seated low to the ground.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a raised-angle right-side perspective view of a drifting kartin accordance with an embodiment of the invention.

FIGS. 2a and 2b are left side views of a drifting kart showing thechange in alignment of a pair of caster wheels caused by rotation of ahand lever in accordance with an embodiment of the invention.

FIGS. 3a and 3b are front views of a drifting kart showing the change inalignment of a pair of caster wheels caused by rotation of a hand leverin accordance with an embodiment of the invention.

FIGS. 4a and 4b are views from below of a drifting kart showing thechange in alignment of a pair of caster wheels caused by rotation of ahand lever in accordance with an embodiment of the invention.

FIGS. 5a and 5b are rear views of a drifting kart showing the change inalignment of a pair of caster wheels caused by rotation of a hand leverin accordance with an embodiment of the invention.

FIGS. 6a and 6b are top views of a drifting kart showing the change inalignment of a pair of caster wheels caused by rotation of a hand leverin accordance with an embodiment of the invention.

FIG. 7 is a raised-angle left-side perspective view of a drifting kartincluding a pair of rear wheels fixed to an axle and a pair of rearcaster wheels, where the rear fixed wheels can be raised and loweredusing a hand lever, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the drawings, drifting karts that are front wheel driveand include rear caster wheels that can be dynamically engaged to induceand control drift during a turn in accordance with embodiments of theinvention are illustrated. A caster wheel typically includes a wheelconfigured to rotate around a rotational axis and a fork supporting thewheel, which enables the wheel to swivel around a swivel axis. When thecaster wheels of the drifting kart contact a track surface and thecaster wheels are free to swivel around their swivel axes, the casterwheels are considered “engaged” and the kart can be steered into adrift. The caster wheels can be “disengaged” to steer the kart normallyby either limiting the extent to which the caster wheels can swivel orby shifting the caster wheels so that they do not contact the tracksurface.

In a number of embodiments, a hand lever controls the engagement of thecaster wheels and can be used by a driver to induce and control driftduring a turn. Pulling on the hand lever simulates a hand brake driftingtechnique used to initiate drift in a rear wheel drive automobile with alimited slip differential. In many embodiments, the caster wheels aremounted to a rotatable member and the hand lever rotates the rotatablemember from a first position, where the caster wheels are aligned sothat the weight of the drifting kart and/or the driver limits theability of the caster wheels to swivel about their swivel axes, to asecond position where the caster wheels are aligned so that they arefree to swivel about their swivel axes during motion of the driftingkart.

In several embodiments, the drifting kart includes an additional pair ofrear wheels fixed to an axle and the hand lever is configured to raiseand lower the fixed wheels so that the caster wheels do not engage thetrack in the lowered position, and the caster wheels engage the track inthe raised position.

In many embodiments, a zero camber zero rake fork houses the powertrain. The power train can be a variable speed electric motor thatdelivers power to a drive wheel using a chain and sprocket system orbelt. In several embodiments, the zero camber zero rake fork enables thefront drive wheel to rotate through 360 degrees. In a number ofembodiments, the alignment of the fork that houses the power train isaligned at an angle to vertical that is sufficiently small such that theweight of the drifting kart and the driver does not prevent the full 360degree steering of the drive wheel. In a number of embodiments, full 360degree drift is not desired and the fork can be aligned at a greaterangle to vertical.

Referring now to FIGS. 1-6 b, views of a drifting kart in accordancewith an embodiment of the invention are illustrated. The drifting kart10 includes a chassis 12, which is typically constructed from hollowtubing that is sufficiently flexible to provide suspension andsufficiently rigid to hold together during driving. A steering mount 14is attached to the chassis and the steering mount supports the steeringassembly and the drive train. In the illustrated embodiment, thesteering assembly includes a steering wheel 16 attached to a steeringcolumn 18 that is configured to rotate a fork 20. The fork 20 containsthe power train, which includes an electric motor 22 that is configuredto drive a steerable wheel 24. In a number of embodiments, the electricmotor 22 is a variable speed DC electric motor that drives the steerablewheel 24 using a chain and sprockets. In several embodiments, theelectric motor 22 drives the steerable wheel 24 using a belt. In manyinstances, the electric motor is a 250 W variable speed electric motor.In other embodiments, any of a variety of electric and/or gasolinemotors can be used to power a drifting kart in accordance withembodiments of the invention. Although a single steerable wheel is shownin FIGS. 1-6 b, two or more steerable wheels can be included in thedrive train. In a number of embodiments, the two or more wheels arealigned to enable steering through 360 degrees.

In several embodiments, the fork is a zero camber zero rake fork thatenables the steering wheel to turn through 360 degrees. The ability toturn the steering wheel through 360 degrees and the ability to inducedrift during the rotation of the steering wheel can provide the driftingkart with a zero turn radius allowing a driver to induce and controldrift that spins the drifting kart through 360 degrees. The verticalalignment of such a fork means that the chassis of the drifting kart isnot raised as the fork is rotated through 360 degrees on a levelsurface. The extent to which the steering column can be aligned at anangle to vertical depends largely upon the weight of the drifting cart,the weight of the driver, and the amount of force the driver can exerton the steering wheel during its turning through 360 degrees.Accordingly, many embodiments utilize forks aligned in accordance withthe requirements of a specific application.

Referring now to FIGS. 3a and 3b , the drifting kart is shown as restingon a pair of rear caster wheels 26. The rear caster wheels are mountedto a rotatable member 40 that is mounted to the chassis 12 using a pairof brackets 42. In the illustrated embodiment, the rotatable member is ahollow tube. In other embodiments, the rotatable member can beconstructed from materials appropriate to the application. A hand lever28, which can be referred to as a “whammy bar”, is connected to therotatable member 40. When the hand lever is lowered, the swivel axes ofthe rear caster wheels are aligned at a sufficiently large angle tovertical that the weight of the drifting kart and/or the driver limitsthe ability of the caster wheels to swivel around their swivel axes.Pulling upward on the hand lever 28 rotates the rotatable member 40. Therotation of the rotatable member 40 rotates the caster wheels under thechassis of the drifting kart and reduces the angles between the swivelaxes of the caster wheels and vertical. Reducing the angles between theswivel axes of the caster wheels and vertical (i.e., the rake) enablesthe caster wheels to rotate more freely around the swivel axis. In thisway, the hand lever can be used to engage the caster wheels and induceand control the amount of drift during a turn. The amount of drift thatis allowed is determined by the angle of the caster wheels. Due to therelationship between the rotatable member and the hand lever, the angleof the caster wheels is controlled by the degree to which the riderlifts the hand lever. In one embodiment, the swivel axis of the casterwheels can rotate between a rake of 33 degrees and 0 degrees to verticalto control the amount of drift that is allowed. In other embodiments,the extent to which the swivel axis of the caster wheels can rotaterelative to vertical is determined by the amount of drift desired in thespecific application.

Referring now to FIGS. 2a, 3a, 4a, 5a, and 6a , the drifting kart isshown with the hand lever lowered. As can be readily observed in FIG. 2a, the swivel axis of the caster wheel 26 is at an angle to vertical andhas a significant component in the direction of the forward motion ofthe drifting kart. Turning now to FIG. 2b , the drifting kart is shownwith the hand lever raised. The swivel axis of the caster wheel 26 isrotated relative to the position shown in FIG. 2a and the caster wheelis free to rotate around its swivel axis.

The caster wheels used in the construction of drifting karts inaccordance with embodiments of the invention are typically constructedfrom high performance casters that include polyurethane wheels mountedto the caster fork via at least one bearing press fitted to the wheel.In one embodiment, the wheels have a 68 mm radius and the bearings areBSB ABEC 7 bearings. Although other casters appropriate to theapplication can also be used.

Power is provided to the power train via a battery housing 30 thatcontains batteries and a controller. The batteries are typicallyrechargeable and employ a recharging system that is configured to drawpower from a conventional single phase power outlet. In manyembodiments, the batteries form a 24 V battery system utilizing two 12 V7 Amp Hour batteries and the controller regulates the supply ofelectricity to the electrical systems of the drifting kart. In otherembodiments, batteries and controls are utilized as necessary for aspecific application. In many embodiments, the battery housing providesa switch for powering the vehicle on or off, as well as a charger portconnection for recharging the batteries. The power generated by thebatteries is channeled to the electric motor, which is typically avariable speed motor, via wires running through the hollow tube chassisof the drifting kart.

In a number of embodiments, an acceleration pedal (not shown, buttypically provided as a foot pedal) connects to a twist throttleaccelerator that controls the power delivered to a variable speedelectric motor in the power train. The twist throttle accelerator can belocated at the rear of the drifting kart adjacent the battery housing.The amount of battery power channeled to the electric motor can beproportionate to how far the acceleration pedal is depressed. Theacceleration pedal can be implemented using a lever similar to a bicyclebrake lever and a bicycle break cable. In other embodiments, theacceleration pedal is implemented using a pedal mechanism and cables,and/or a variety of techniques are used to control the power deliveredto the steerable wheel by the drive train.

A seat 32 for the driver is also mounted to the chassis. The seat istypically positioned so that the driver is readily able to rotate thesteering wheel and pull upward on the hand lever from a comfortabledriving position. For stability, the seat is typically fixed to thechassis as low to the ground as possible. The higher the seat thegreater the likelihood that shifting weight will cause the drifting kartto roll during cornering. In a number of embodiments, the seat 32 islocated in front of the battery housing 30. In other embodiments, thebattery housing is located in accordance with the requirements of theapplication.

Referring back to the caster wheels 26 in FIGS. 1-6 b, a rotatablemember is used to engage the rear caster wheels 26. In otherembodiments, a variety of techniques are used to dynamically engage therear caster wheels to induce and control drift during a turn. Turningnow to FIG. 7 a drifting kart in accordance with an embodiment isillustrated. The drifting kart 100 shown in FIG. 7 is similar to thedrifting kart 10 shown in FIGS. 1-6 b with the exception that thedrifting kart 100 includes an additional set of fixed rear wheels 102connected via an axle 104. In the illustrated embodiment, the hand lever28′ enables the raising and lowering of the fixed rear wheels 102 andthe rear caster wheels 26′ are engaged by using the hand lever 28′ toraise the fixed rear wheels. Raising the fixed rear wheels 102 placesthe rear caster wheels 26′ in contact with the track beneath thedrifting kart. In this way, the hand lever can be used to engage therear caster wheels and induce and control drift during a turn. Althoughthe fixed rear wheels are raised and lowered in the embodimentillustrated in FIG. 7, drifting karts in accordance with embodiments ofthe invention can utilize rear caster wheels that can be raised andlowered. In embodiments where the rear caster wheels are raised andlowered using a “whammy bar” mechanism similar to that shown in FIGS.1-6 b that raises and lowers the caster wheels by rotating them underthe chassis, the “whammy bar” can be used to dynamically engage thecaster wheels to induce and control drift during a turn.

Although use of the “whammy bar” mechanism described above is discussedwith reference to drifting karts, similar mechanisms involving modifyingthe rake of one or more caster wheels to control the extent to which thecaster wheel can swivel around its swivel axis can be utilized in avariety of other powered and non-powered vehicles and/or devices. Whenincorporated into a device, the “whammy bar” mechanism typicallyinvolves at least one caster wheel mounted to a rotatable member thatcan be rotated using a lever to control the rake of the caster wheel.

While the above description contains many specific embodiments of theinvention, these should not be construed as limitations on the scope ofthe invention, but rather as an example of one embodiment thereof. Forexample, other mechanisms can be used to dynamically engage casterwheels and induce and control drift during a turn including but notlimited to mechanisms that mechanically and controllably limit theability of the caster wheels to swivel around their swivel axes.Accordingly, the scope of the invention should be determined not by theembodiments illustrated, but by the appended claims and theirequivalents.

What is claimed is:
 1. A ridable vehicle comprising: a chassis having aforward portion and a rearward portion; a steering mount coupled to theforward portion of the chassis, wherein the steering mount comprises afirst portion, a second portion, and an intermediate portion, whereinthe first portion is positioned forward of the second portion and theintermediate portion connects the first portion with the second portion,wherein the steering mount is substantially aligned with a longitudinalaxis of the vehicle, wherein the steering mount comprises a steeringassembly configured to support a fork, the fork configured to support amotor; a seat coupled to the chassis, wherein the seat is positionedadjacent the second portion of the steering mount, at least two casterwheels coupled to the rearward portion of the chassis, wherein thecaster wheels are configured to rotate about a rotational axis andswivel about a swivel axis, wherein the swivel axis is substantiallystationary relative to chassis; wherein the motor is configured to drivethe front wheel.
 2. The ridable vehicle of claim 1, wherein the steeringmount comprises a substantially trapezoidal shape from a side vantagepoint of the ridable vehicle.
 3. The ridable vehicle of claim 1, whereinthe intermediate portion is generally parallel with a longitudinal axisof the vehicle.
 4. The ridable vehicle of claim 1, wherein a front endof the seat is positioned adjacent a lower portion of the second portionof the steering mount.
 5. The ridable vehicle of claim 1, wherein theseat is positioned above the chassis.
 6. The ridable vehicle of claim 1,wherein the steering assembly extends through an aperture in theintermediate portion.
 7. The ridable vehicle of claim 1, wherein a baseof the seat is positioned approximately aligned with a lateral axis thatis perpendicular to a swivel axis of the caster wheels.
 8. The ridablevehicle of claim 1, wherein the motor is a variable speed electricmotor.
 9. The ridable vehicle of claim 8, wherein the power delivered tothe variable speed electric motor is controlled by an accelerationpedal.
 10. The ridable vehicle of claim 1, wherein the caster wheels arecoupled to the chassis via a rotatable member that is coupled to a handlever coupled to the chassis and rotation of the hand lever rotates thecaster wheels from a first position where the caster wheels are alignedso that the weight on the caster wheels limits the ability of the casterwheels to swivel about their swivel axes, to a second position where thecaster wheels are aligned so that they are free to swivel about theirswivel axes.
 11. A ridable vehicle comprising: a chassis having aforward portion and a rearward portion; a steering mount coupled to theforward portion of the chassis, wherein the steering mount comprises afirst portion and a second portion, wherein the first portion ispositioned forward of the second portion, wherein the steering mount issubstantially aligned with a longitudinal axis of the vehicle, whereinthe steering mount comprises a steering assembly configured to support afork, the fork configured to support a steering wheel and a motor; aseat coupled to the chassis, the seat comprising a base and a rearportion, at least two caster wheels coupled to the rearward portion ofthe chassis, wherein the caster wheels are configured to rotate about arotational axis and swivel about a swivel axis, wherein the swivel axisis substantially stationary relative to chassis; wherein the motor isconfigured to drive the front wheel, and wherein the rear portion of theseat is positioned rearward of a connection between the caster wheelsand the chassis.
 12. The ridable vehicle of claim 11, wherein the seatis positioned entirely below the steering wheel.
 13. The ridable vehicleof claim 11, wherein the motor is a variable speed electric motor. 14.The ridable vehicle of claim 11, wherein the caster wheels are coupledto the chassis via a rotatable member that is coupled to a hand levercoupled to the chassis and rotation of the hand lever rotates the casterwheels from a first position where the caster wheels are aligned so thatthe weight on the caster wheels limits the ability of the caster wheelsto swivel about their swivel axes, to a second position where the casterwheels are aligned so that they are free to swivel about their swivelaxes.
 15. The ridable vehicle of claim 11, wherein the steering mountcomprises a substantially trapezoidal shape from a side vantage point ofthe ridable vehicle.
 16. The ridable vehicle of claim 11, wherein afront end of the seat is positioned adjacent a lower portion of thesecond portion of the steering mount.
 17. The ridable vehicle of claim11, wherein the first portion and the second portion of the steeringmount are angled relative to a longitudinal axis of the chassis.
 18. Theridable vehicle of claim 11, wherein the base of the seat is positionedapproximately aligned with a lateral axis that is perpendicular to aswivel axis of the caster wheels.
 19. The ridable vehicle of claim 11,wherein the swivel axis is rearward of the connection between the casterwheels and the chassis.
 20. A method comprising: obtaining a cartcomprising: a chassis comprising a forward portion and a rearwardportion; a steering mount coupled to the forward portion of the chassis;a seat coupled to the chassis; a front wheel; a motor; and at least twocaster wheels coupled to the rearward portion of the chassis andconfigured to rotate about a rotational axis and swivel about a fixedswivel axis; driving the front wheel with the motor; receiving a turninginput to turn the front wheel and to induce a turn of the cart; andengaging the caster wheels to provide drifting movement of the cartduring the turn.